Direct Radiating Array Antenna Assembly

Abstract

A direct radiating array ("DRA") antenna is provided that includes a printed circuit board ("PCB") having a first side and a second side opposite the first side, a thermal interface plate disposed generally parallel to the PCB, a plurality of radiating elements mounted to the first side of the PCB, a plurality of radio frequency ("RF") chains mounted to the second side of the PCB and to the thermal interface plate, each respective one of the plurality of RF chains being coupled to and positioned proximate to a respective one of the plurality of radiating elements and thermally coupled to the thermal interface plate, and a plurality of beam forming circuits mounted to the second side of the PCB, each of the RF chains being connected to at least one of the plurality of beam forming circuits.

Description

[Technical field]

[0001] The following relates to antennas and antenna assemblies for radio frequency (RF) communications, and more particularly to direct radiating array antennas. [Background technology]

[0002] As the number of connected devices and the need for communication therebetween continues to increase along with the generation and proliferation of data generated by such devices, the demand for communication systems to facilitate such communication also continues to increase. One such mode of facilitating communication is by communication satellites. As it becomes easier to launch satellites into space and the demand for satellite-based communication increases, the market for communication satellites is beginning to explode.

[0003] Communications satellites facilitate communications through on-board antennas. One such example of an antenna is an active direct radiating array antenna. It is important for such antennas to manage and balance size, mass, and power. It is often desirable to have an antenna that can provide any one or more of reduced size, reduced mass, or reduced power consumption, or that can provide performance tradeoffs while effectively managing the antenna's size, mass, and power. For example, in spaceborne applications, the overall weight allocated for the antenna may be constrained, thereby limiting the number of radiating elements and the performance of the antenna.

[0004] The continuous increase in the frequency bands of signals for communication, and the amount of beams carrying the signals, can make it increasingly difficult to have a significant number of mechanical and electrical components concentrated in close proximity to the array while maintaining antenna efficiency, especially for Low Earth Orbit applications. LEO creates greater DRA scanning requirements, which in turn make element spacing (i.e., spacing between radiating elements) tighter. Thus, LEO is much more challenging than GEO or MEO in terms of closely concentrated mechanical and electrical components. To reduce signal loss through different components, such components may need to be positioned as close as possible to the aperture of the array to limit signal path lengths as much as possible.

[0005] There is also a need to effectively manage heat generated by the antenna's components, such as signal amplifiers and other electrical, electronic, and electromechanical components, to avoid temperature increases that can reduce overall antenna performance. Thus, structures for dissipating heat generated by the antenna components may be desirable. However, such structures may complicate the overall integration of the antenna. As a result, the weight of antennas, such as direct radiating arrays, may be significant, which may adversely affect the satellite mission.

[0006] The structural requirements of the antenna (e.g., interface plates, mechanical supports, radiating elements, signal amplification paths, and structures for dissipating heat) can be significant and can require significant physical volume, which can increase the weight of the antenna and reduce the available space on the spacecraft. In spaceborne applications, the overall weight and available space allocated for the antenna can be limited, which can limit the number of radiating elements and reduce the performance of the antenna.

[0007] Satellites may use optical communications links, which require line of sight access for proper operation. Some current DRA antenna assembly units may include a relatively high profile, which can impede the line of sight of the optical head communications link and reduce the effectiveness of the optical communications link.

[0008] Additionally, when deployed in the space environment, the antenna may be subject to a variety of wave and particle radiation, which may interfere with the operation of the antenna. To ensure proper performance of the antenna, radiation shielding of certain sensitive components may be required. Such radiation shielding may increase the weight of the antenna, further reducing the available space on the spacecraft.

[0009] Thus, a need exists for an improved directly radiating array antenna and assembly method that overcomes at least some of the disadvantages of existing directly radiating array systems and methods. Summary of the Invention [Means for solving the problem]

[0010] According to an embodiment, described herein is a direct radiating array ("DRA") antenna including a printed circuit board ("PCB") having a first side and a second side opposite the first side, a thermal interface plate disposed generally parallel to the PCB, a plurality of radiating elements mounted on the first side of the PCB, a plurality of radio frequency ("RF") chains mounted on the second side of the PCB and to the thermal interface plate, each respective one of the plurality of RF chains coupled to and positioned proximate to a respective one of the plurality of radiating elements and thermally coupled to the thermal interface plate, and a plurality of beam forming circuits mounted on the second side of the PCB, each of the RF chains connected to at least one of the plurality of beam forming circuits.

[0011] According to some embodiments, the RF chains are arranged in a plurality of stacks, each respective one of the plurality of stacks being mounted to the second side of the PCB and extending generally perpendicular to the second side of the PCB.

[0012] According to some embodiments, the radiating element is a patch radiating element.

[0013] According to some embodiments, the PCB includes one or more radiation-shielding copper layers embedded within the PCB and positioned to shield electrical, electronic, or electromechanical components of the DRA antenna from radiation.

[0014] According to some embodiments, the thermal interface plate includes a plurality of fluid channels.

[0015] According to some embodiments, the thermal interface plate, when mounted on a movable or stationary structure, acts as the sole thermal spreader and the DRA antenna's conductive and radiative exchange interface with the movable or stationary structure.

[0016] According to some embodiments, the mobile or stationary structure is a spacecraft.

[0017] According to some embodiments, the mobile or stationary structure is a low earth orbit satellite.

[0018] According to some embodiments, each of the plurality of stacks is connected to a thermal interface plate via one or more thermal interface materials.

[0019] According to another embodiment, described herein is a DRA antenna including a printed circuit board ("PCB") having a first side and a second side opposite the first side, a plurality of radiating elements mounted on the first side of the PCB, and a plurality of RF chains each coupled to a respective one of the plurality of radiating elements, the plurality of RF chains being arranged in a plurality of stacks, each respective one of the plurality of stacks being mounted on a second side of the PCB and extending generally perpendicular to the second side of the PCB.

[0020] According to some embodiments, the radiating element comprises a patch radiating element.

[0021] According to some embodiments, the beamforming circuitry is configured to perform digital beamforming.

[0022] According to some embodiments, the beamforming circuitry is configured to perform analog beamforming.

[0023] Other aspects and features will become apparent to those of ordinary skill in the art upon review of the following description of several exemplary embodiments.

[0024] The drawings included herein are intended to illustrate various examples of the articles, methods, and apparatus herein. [Brief description of the drawings]

[0025] [Figure 1] FIG. 1 illustrates a perspective view of a direct radiating array (DRA) antenna assembly configured for transmission, according to an embodiment. [Figure 2A] FIG. 2 is a top view of the transmit configured direct radiating array (DRA) antenna assembly of FIG. 1, in accordance with an embodiment. [Figure 2B] FIG. 2 is a front view of the transmit configured direct radiating array (DRA) antenna assembly of FIG. 1 in accordance with an embodiment. [Figure 2C] FIG. 2 is a side view of the transmit configured direct radiating array (DRA) antenna assembly of FIG. 1 in accordance with an embodiment. [Figure 3A] FIG. 3 is an exploded view of the transmit configured direct radiating array (DRA) antenna assembly of FIGS. 1-2, according to an embodiment. [Figure 3B] 3B is an expanded exploded view of the transmit configured direct radiating array (DRA) antenna assembly of FIG. 3A, in accordance with an embodiment. [Figure 4] FIG. 1 illustrates a perspective view of a direct radiating array (DRA) antenna assembly configured for receiving, according to an embodiment. [Figure 5A] FIG. 5 is a top view of the receive configured direct radiating array (DRA) antenna assembly of FIG. 4, in accordance with an embodiment. [Figure 5B] FIG. 5 is a side view of the receive configured direct radiating array (DRA) antenna assembly of FIG. 4, in accordance with an embodiment. [Figure 5C] FIG. 5 is a front view of the receive configured direct radiating array (DRA) antenna assembly of FIG. 4 in accordance with an embodiment. [Figure 6A] FIG. 6 is an exploded view of the receive configured direct radiating array (DRA) antenna assembly of FIGS. 4-5, according to an embodiment. [Figure 6B] 6B is an expanded exploded view of the receive configured direct radiating array (DRA) antenna assembly of FIG. 6A, according to an embodiment. [Figure 7] FIG. 4 is a perspective view of a PCB of the transmit configured direct radiating array (DRA) antenna assembly of FIGS. 1-3, according to an embodiment. [Figure 8] FIG. 4 is a top view of a PCB of the transmit configured direct radiating array (DRA) antenna assembly of FIGS. 1-3 according to an embodiment. [Figure 9] FIG. 4 is a perspective view of an RF chain cluster of the transmit configured direct radiating array (DRA) antenna assembly of FIGS. 1-3 in isolation, according to an embodiment. [Figure 10] FIG. 4 is a plan view of an RF chain cluster of the transmit configured direct radiating array (DRA) antenna assembly of FIGS. 1-3 in isolation, according to an embodiment. [Figure 11] FIG. 4 is a cross-sectional view of the transmit configured direct radiating array (DRA) antenna assembly of FIGS. 1-3, according to an embodiment. [Figure 12] FIG. 4 is a cross-sectional view of the transmit configured direct radiating array (DRA) antenna assembly of FIGS. 1-3 including a spacecraft heat pipe, illustrating heat transfer from the DRA to the heat pipe, according to an embodiment. [Figure 13] FIG. 4 is a partially transparent perspective view of a portion of a PCB of the transmit configured direct radiating array (DRA) antenna assembly of FIGS. 1-3, further including a radiation shield, according to an embodiment. [Figure 14] FIG. 4 is a partially transparent top view of a portion of a PCB of the transmit configured direct radiating array (DRA) antenna assembly of FIGS. 1-3, further including a radiation shield, according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] Various devices or processes will be described below to provide examples of each claimed embodiment. The embodiments described below are not intended to limit any claimed embodiment, and any claimed embodiment may cover a process or device different from that described below. The claimed embodiments are not limited to a device or process having all of the features of any one device or process described below, or to features common to more than one or all of the devices described below.

[0027] The following relates generally to antenna-based communication systems, and more specifically to direct radiating array ("DRA") antennas. Although the DRA antenna assemblies of the present disclosure are described in the context of space-based applications (e.g., on satellites or other spacecraft), it should be understood that the DRA antenna assemblies can be used in non-space applications (e.g., on ground terminals, etc.), and such uses are contemplated by the present disclosure. In an alternative, the DRA antennas of the present disclosure can be configured for digital beamforming or analog beamforming.

[0028] The DRA of the present disclosure can be more compact or low profile than existing DRAs. The low profile configuration can result in improved visibility of surrounding equipment (e.g., compared to a taller DRA) since the DRA may be out of line of sight of other equipment, such as an optical inter-satellite link. This can advantageously reduce size, cost, and / or mass, which may be an important factor in implementing a DRA in space-based applications. Compactly packaging amplifiers, filters, polarizers, and other electrical components below the radiating element (e.g., on the opposite side (side 1) of the PCB from the radiating element) places dissipative / heat producing components on the PCB (side 2) for heat removal. This PCB configuration also facilitates PCB assembly since components are attached to only one side of the PCB, resulting in fewer setup and inspection operations and reducing assembly time. Thermal interface materials pose challenges regarding reworkability. For example, a single-use adhesive may be preferred in some instances, which may not be easily removed. In other instances, a gasket may be used, which may damage electrical components through compression. Because there is only a single thermal interface, less thermal interface material may need to be installed in the DRA. Such a configuration may allow the thermal components of the DRA to be assembled at a single assembly station.

[0029] The DRA of the present disclosure can use three-dimensional stacked packaging of electrical components on or attached to a PCB. This stacked packaging solves the PCB footprint problem and also solves radiation problems to some extent because some components can be shielded by components below in the three-dimensional component stack. Additionally, highly integrated monolithic microwave integrated circuits, substrates, and other electronic components can be applied in the DRA of the present disclosure along with printed RF assemblies, connectorized interfaces, direct waveguide interfaces, wire bonded interfaces, pin / socket interfaces, ball grid array / land grid array interfaces, surface mount technology interfaces, micromachined radio frequency components, traditional SIPs, bare die, monolithic microwave integrated circuits, ceramic or alumina filters, 3D printed filters. This mix of technologies can be used to provide multiple physical levels of interconnectivity while placing dissipative / heat producing components on top of the three-dimensional stack to remove heat directly to a thermal sink. The dissipative components can include DC power components, such as voltage regulators, beam forming integrated circuits, and RF amplification components, such as drivers, pre-drivers, or high power amplifiers. Additionally, this three-dimensional stacked packaging provides additional design freedom to control the coefficient of thermal expansion stack up, such that the DRA thermal fatigue life can be optimized.

[0030] The DRA of the present disclosure is configured such that all active RF electronic components are mounted on one side of one PCB. Due to this mounting, these components are all thermally coupled to a single cold plate, thus realizing high thermal efficiency. The cold plate can be positioned in direct contact with the spacecraft thermal control hardware (which can include, for example, heat pipes embedded in or on the spacecraft panel), which allows for a smaller DRA package and reduces the thermal management difficulties at the DRA level. Such an arrangement avoids duplication of thermal hardware between the DRA and the spacecraft, thus reducing the overall mass and cost at the spacecraft level. Mounting the DRA directly on the spacecraft panel can minimize the height of the mounted assembly and reduces the possibility of blocking any surrounding RF or optical equipment.

[0031] The cold plate of the DRA can be constructed from a highly conductive material and can be configured to have fluid channels running through the thermal plane / cold plate. In an embodiment, all heat sources of the DRA are connected to the cold plate through a thermal interface material. A single-plane cold plate (single-plane thermal interface) reduces the number of thermal interfaces and increases the overall thermal efficiency of the assembly by collecting heat from the DRA and transporting it directly to the spacecraft heat sink while maintaining a small thermal gradient between the source and sink. The single-plane configuration can also ensure that the dissipative components are not mechanically separated from the heat sink. The thermal design of the DRA of the present disclosure can be largely conductive and can be configured to collect and transport heat between different sources with the lowest possible thermal gradient along the way. The thermal interface plate can act as the main thermal highway to which the main dissipative components of the DRA are connected and can be configured to transfer heat dissipated into the DRA to a spacecraft thermal interface (e.g., heat pipes) located below and / or centrally at the periphery of the DRA. Thermal path lengths can be optimized by configuring the DRA so that the spacecraft thermal interface or heat pipe is in the center of the DRA or under an area of ​​the DRA rather than on two sides. The spacecraft heat pipe routing described herein can eliminate the need to transport heat laterally, but rather dump the heat directly into the spacecraft thermal subsystem. Additionally, auxiliary hardware can be installed on the sides of the PCB that contains the radiating elements.

[0032] In some embodiments, the PCB of the DRA of the present disclosure is configured to include one or more dedicated copper planes in the PCB as radiation shielding for the radiation-sensitive electrical components of the DRA. The flat configuration of the DRA of the present disclosure has less metal hardware between the external radiation source and the electrical components, which can cause the electrical components (electrical, electronic, and electromechanical components) of the DRA to be exposed to radiation. In addition to one or more copper plane radiation shields, copper planes can also be present in the PCB layers for grounding, thermal management, and RF / digital signals. Copper islands can be added in the PCB, for example, using ray tracing-based analysis, where the function of the copper islands is to shield the radiation-sensitive electrical components of the DRA assembly.

[0033] In some embodiments, the DRA can further include a sunshield over the antenna aperture for thermal management such that peak-to-peak temperatures can be reduced. Such a sunshield can provide protection against direct radiation exposure to atomic oxygen ram flux.

[0034] Referring now to FIG. 1, shown therein is a perspective view of a direct radiating array ("DRA") antenna assembly 100-1, according to an embodiment.

[0035] Assembly 100-1 in FIG. 1 is a direct radiating array assembly 100-1 configured for transmission (Tx). Assembly 100-1 is configured to be coupled to a spacecraft to enable communication from the spacecraft to another spacecraft or to a ground terminal or mobile terminal. In other embodiments, assembly 100-1 can be used as a ground terminal on a mobile or stationary platform or structure. For example, assembly 100-1, or other embodiments, can be coupled to a vehicle, automobile, truck, cargo container, aircraft, mobile home, boat, cruise ship, yacht, building, mast (cellular or radio), or structure other than a spacecraft.

[0036] Assembly 100-1 is configured to receive digital input signals from an on-board processor of a spacecraft, perform digital beamforming operations on at least a portion of the digital input signals, and transmit beamformed RF signals corresponding to at least a portion of the digital input signals to another terminal (e.g., a movable terminal such as a spacecraft or a ground terminal). In other embodiments, the DRA assembly may be configured to perform analog beamforming operations and may receive analog and / or RF input signals.

[0037] In general, the assembly 100-1 can be a phased array antenna assembly, which includes a collection of antenna / radiating elements 112-1 assembled together such that the radiation pattern of each respective radiating element 112-1 combines constructively with neighboring radiating elements 112-1 to form an effective radiation pattern called the main lobe. The main lobe transmits radiated energy in the desired location while the assembly 100-1 is designed to destructively interfere with signals in undesired directions to form nulls and side lobes. The assembly 100-1 can be designed to maximize the energy radiated in the main lobe while reducing the energy radiated in the side lobes to an acceptable level. The direction of radiation can be manipulated by varying the phase of the signal fed into each antenna element 112-1. The result is that each antenna element 112-1 in the array has an independent phase and amplitude setting to form the desired radiation pattern. Assembly 100-1 uses digital circuit-based phase adjustment to vary the direction of the radiation pattern.

[0038] Assembly 100-1 is capable of dual or single polarization operation and can be configured to operate in any RF frequency band.

[0039] The assembly 100-1 includes a front printed circuit board (PCB) housing 102-1, a calibration antenna 104-1, a PCB 106-1 having a front side 108-1 and a rear side 110-1 (as depicted in FIG. 3), and an interface plate 114-1. The front side 108-1 additionally includes an array of radiating elements 112-1, each element 112-1 being an antenna configured to transmit a radio frequency signal. In one embodiment, the radiating elements can be patch radiating elements. In other embodiments, the radiating elements can be another type of radiating element. For example, the radiating elements can be dipoles or printed spirals. The assembly 100-1 is configured such that the assembly 100-1 has a lower profile than other dynamic radiating array antenna assemblies.

[0040] The front PCB housing 102-1 is a structural component configured to secure the PCB 106-1 to the interface plate 114-1. The front PCB housing 102-1 includes a metal frame configured to fit over and around the PCB 106-1 such that the front PCB housing 102-1 can secure the PCB 106-1 when the front PCB housing 102-1 is secured to another structure or surface. The front PCB housing 102-1 can include a number of mounting holes such that machine screws or bolts or other mechanical fasteners can be used to secure the front PCB housing 102-1 to another component, such as the interface plate 114-1. In the example of FIGS. 1-3, the front PCB housing 102-1 is constructed from metal. In other examples, the front PCB housing 102-1 can be constructed from other materials, such as polyetheretherketone, carbon fiber, other polymers, or other composite materials. The front PCB housing 102-1 may be machined, welded, brazed, cast, or additively manufactured, and if constructed from a radiation-shielding material, such as metal, may provide added radiation shielding in limited orientations for electronic components mounted on the rear side 110-1 of the PCB 106-1.

[0041] The calibration antenna 104-1 includes an antenna device configured to receive RF signals in the same RF band as emitted by the assembly 100-1, such that the output of the radiating element 112-1 can be accessed by the calibration antenna 104-1. The assembly 100-1 includes a plurality of calibration antennas 104-1, each of which is attached to or otherwise mechanically integrated into the interface plate 114-1. In other embodiments, the calibration antennas 104-1 can be mechanically integrated into the assembly 100-1 through other components. In one embodiment, the number of calibration antennas can be four. Each calibration antenna 104 can acquire received RF signal data and pass the acquired data back to the spacecraft and / or on-board processor of the assembly 100-1 so that RF transmission parameters, such as beamforming parameters, of the assembly 100-1 can be adjusted according to feedback received from the calibration antenna 104-1. Such adjustments can enable higher RF performance or a longer lifespan of the assembly 100-1 because the assembly 100-1 can be adjusted to account for aging effects, temperature changes, or other factors. In some examples, the calibration electronics associated with the calibration antenna 104-1 can be integrated into or mounted on the PCB 106-1 and / or integrated into the beamforming circuitry.

[0042] PCB 106-1 is a multi-layer printed circuit board including a front side 108-1 and a rear side 110-1 (depicted in FIG. 3). PCB 106-1 is a generally rectangular circuit board with cut corners such that PCB 106-1 includes four long edges and four short edges. The number of layers in the PCB can vary. In other embodiments, PCB 106-1 can include fewer or more layers. In embodiments using analog beamforming, PCB 106-1 can include more layers. In other examples, the PCB can include different shapes, such as round or hexagonal shapes.

[0043] On the front side 108-1, the PCB 106-1 includes an array of patch radiating elements 112-1. Each element 112-1 is an antenna configured to transmit a radio frequency signal. Each patch radiating element 112-1 is a generally hexagonal antenna with a generally circular exposed metal portion. Each hexagonal radiating element 112-1 can be tessellated such that the radiating elements 112-1 entirely cover a continuous surface of the PCB 106-1 with few gaps. In some examples, each radiating element can be constructed from gold, copper, aluminum, or silver alloy, or can be plated with gold, copper, aluminum, silver, or gold, copper, aluminum, or silver alloy. Each radiating element 112-1 is coupled to an RF driver circuit such that each radiating element 112-1 provides a separate signal. The number of radiating elements 112-1 in the assembly 100-1 can be determined based on multiple design factors, such as tradeoffs between power consumption, cost, and / or directivity. In some examples, the radiating elements 112-1 can include micromachined cross dipoles with integrated polarizers and filters (e.g., integrated into a single subassembly that can be mounted on the PCB 106-1), aluminum carrier chunks, air-gapped patches, integrated patches, waveguide elements, probe and cup elements, helical elements, or other elements. In some examples, the radiating elements 112-1 can include square radiating elements or round radiating elements arranged in a square grid. In variations, the radiating elements 112-1 can be arranged in or placed on a square or rectangular grid or an irregular grid.

[0044] At the rear side 110-1, the PCB 106-1 includes a number of electrical components. The electrical components include surface mounted devices (SMDs). The SMDs are mounted on a surface of the rear side 110-1 of the PCB 106-1. The SMDs can be mounted on the surface 110-1 using a bonding technique or through a connectorized interface. The connectorized interface can be, for example, a pin and socket interface. In one embodiment, the SMDs can be soldered onto the surface 110-1. In other embodiments, the SMDs can be mounted on the surface 110-1 using other suitable bonding techniques. The SMDs can include amplifiers, filters, polarizers, and analog or digital beamforming circuits. In some cases, the SMDs can be indirectly mounted to the PCB 106-1 through another SMD (e.g., by mounting one SMD to another SMD). The digital beamforming circuitry can include multiple integrated circuits, such as application specific integrated circuits (ASICs). In other embodiments, the SMD may further include capacitors, resistors, inductors, isolators, and other integrated circuits. Contacts present on the SMD mounted on the rear side 110-1 may be routed through the PCB 106-traces to the radiating element 112-1 such that the SMD mounted on the rear side 110-1 may drive the radiating element 112-1.

[0045] The assembly 100-1 may be particularly susceptible to radiation interference due to its relatively low profile, since fewer inherently radiation-shielding components may be between the radiation source and the radiation-sensitive components. In some embodiments, copper layers or planes may be present in the PCB 106-1 such that electrical components on the rear side 110-1 of the PCB 106-1 may be shielded from radiation. Some of these copper layers may be present solely for radiation-shielding functionality. For example, in a space-based application of the assembly 100-1, the front side 108-1 of the PCB 106-1 may be exposed to space during operation of the assembly 100-1. Radiation originating from space may strike the front side 108-1 of the PCB 106-1. The radiation-sensitive electrical components of the assembly 100-1 may be located on the rear side 110-1 of the PCB 106-1 to limit radiation exposure. However, higher energy radiation can penetrate through the PCB 106-1 to the rear side 110-1 of the PCB 106-1, resulting in radiation exposure to sensitive electrical components located on the rear side 110-1 of the PCB 106-1. The presence of a radiation shielding copper layer in the PCB 106-1 can advantageously prevent radiation from penetrating through the PCB 106-1 and interfering with sensitive electrical components on the rear side 110-1 of the PCB 106-1 because some radiation cannot easily penetrate the radiation shielding copper layer in the PCB 106-1. Also, the front PCB housing 102-1 can reduce the probability of high energy radiation impinging on the PCB 106-1 from shallow angles by shielding some radiation.

[0046] The placement and shape of the radiation shielding copper layers in PCB 106-1 can be determined by application of ray tracing, where the spacecraft's operational position and orientation is known. Using integrated PCB copper layers for radiation shielding, as compared to separate radiation shielding components, can enable production of assembly 100-1 having a smaller volume and / or mass, which can be advantageous for space applications where volume and mass can be important constraints.

[0047] 2A-2C (collectively referred to as FIG. 2), shown therein are isometric views of assembly 100-1 of FIG. 1, including top, side, and front views, respectively. Visible in the isometric views are the front and side of assembly 100-1. The embodiment of FIGS. 1-2 includes a relatively low profile assembly 100-1, as seen in the front and side views of FIGS. 2C and 2B, respectively.

[0048] 3A and 3B (collectively referred to as FIG. 3), shown therein is an exploded view of the assembly 100-1 of FIG. 1 and FIG. 2. Also shown in FIG. 3 are a connector cover 116-1, a power converter (EPC) 118-1 (mounted around or below the PCB 106-1), and an RF chain 120-1. The connector cover may include covers for digital, radio frequency, telemetry and telecommand interfaces, or power connectors.

[0049] The interface plate 114-1 is a generally planar plate configured to attach to the front PCB housing 102-1 such that when the interface plate 114-1 and the front PCB housing 102-1 are secured to one another, the PCB 106 can be securely secured between the interface plate 114-1 and the front PCB housing 102-1.

[0050] The interface plate 114-1 includes a number of mounting holes for mounting the assembly 100-1 to a spacecraft by attaching the interface plate 114-1 to the spacecraft with mechanical fasteners, which can be, for example, machine screws.

[0051] The interface plate 114-1 is configured to promote heat transfer away from the heat producing or dissipative components of the assembly 100-1. The interface plate 114-1 is preferably constructed from a material having a high thermal conductivity, such as an aluminum alloy, a controlled expansion tailored metal with a customizable ratio of fibers, particulates, or powder loadings, copper, or a copper alloy. The interface plate 114-1 is configured to allow the heat producing components of the assembly 100-1 to easily conduct heat into the interface plate 114-1. For example, the surface of the interface plate 114-1 can match the height variations of the electrical components present on the rear side 110-1 of the PCB, such that the electrical components are in physical contact with the interface plate 114-1, allowing heat transfer from the electrical components to the interface plate 114-1.

[0052] In the example of FIGS. 1-3, the interface plate 114-1 further includes microfluidic channels. The microfluidic channels can be passive fluid channels. The microfluidic channels are configured to promote greater heat transfer through the interface plate 114-1. The microfluidic channels can be filled with a conductive fluid, which can improve the overall thermal conductivity of the interface plate 114-1. In some examples, the conductive fluid can include a multiphase fluid that includes a phase change point at a temperature near the operating temperature of the assembly 100-1, such that the conductive fluid can undergo a phase change during operation of the assembly 100-1, which can further increase the overall thermal conductivity of the interface plate 114-1. The fluidic channels in the interface plate 114-1 can be capable of handling a higher heat flux in a lower volume, which can provide significant mass savings. In some embodiments, the fluidic channels of the interface plate 114-1 can be routed to the periphery of the array. A thermal interface material can be selected to connect the dissipative electrical, electronic, and electromechanical components of the DRA 100-1 to the thermal interface plate 114-1 that exerts only a small compressive force. In other embodiments, copper and / or water filled heat pipes can be integrated into the interface plate 114-1 to promote greater heat transfer rates.

[0053] The connector cover 116-1 includes a physical cover that can be placed over the connector components present on the PCB 106-1. The connector cover 116-1 can protect the covered protector from physical and chemical damage.

[0054] EPC 118-1 includes power supply components configured to receive a supply of power from a spacecraft power source and output power with the specifications required to power the components of assembly 100-1. In some embodiments, EPC 118-1 can be mounted directly to interface plate 114-1 or can be mounted remotely and connected to assembly 100-1 by a cable.

[0055] RF chain 120-1 includes electrical components configured to receive digital input signals from the spacecraft's on-board processor and output drive signals to radiating elements 112-1. RF chain 120-1 may include digital beamforming circuits (e.g., ASICs), digital-to-analog converters, amplifiers, polarizers, filters, and other integrated circuits.

[0056] 4-6, shown therein are various views of a direct radiating array assembly 100-2 configured for receiving (Rx), according to an embodiment. FIGS. 4-6 are similar to FIGS. 1-3, respectively. The description provided above with reference to FIGS. 1-3 also applies to FIGS. 4-6. Assembly 100-2 differs from assembly 100-1 in that assembly 100-1 is configured to transmit beamformed RF signals, while assembly 100-2 is configured to receive RF signals. Assembly 100-2 includes similar components to assembly 100-1. Descriptions of components with reference letters appended with "-1" correspond to components with reference letters appended with "-2".

[0057] The Rx DRA assembly 100-2 may operate in dual polarization or single polarization, or may be configured to operate in the L / S frequency band or the C frequency band (e.g., an L / S or C flat DRA).

[0058] RF chain 120-2 is configured to receive as an input the RF signal received by radiating element 112-2 and convert the RF signal into a beamformed digital signal that can be provided to the spacecraft's on-board processor for analysis.

[0059] The thermal design of the assembly 100-2 may be different because fewer / lower power dissipation components may be present in the Rx assembly 100-2, which may require less thermal control hardware and smaller thermal interfaces.

[0060] Referring now to FIG. 7, shown therein is a detailed perspective view of rear side 110-1 of PCB 106-1 of assembly 100-1 in an isolated state.

[0061] Visible on PCB 106-1 are multiple RF chain components 120-1. In the embodiment of FIGS. 1-3 and 7, 96 stacks of RF chain components 120-1 are depicted. In other embodiments of assemblies 100-1, 100-2, there may be a different number of sets of RF chain components 120-1. The number of RF chain components 120-1 may generally be proportional to the total number of radiating elements 112-1 in each assembly 100-1. In assembly 100-1, 96 stacks of RF chain components 212 feed the entire radiating element 112-1. In other embodiments, fewer or more stacks of RF chain components may be present for a fixed number of radiating elements. The number of components in each stack may vary in the embodiments.

[0062] Generally, the RF chain components 120-1 associated with the radiating element 112-1 may be positioned across the PCB 106-1 directly across from the radiating element. This may minimize the conductive path length between the radiating element 112-1 and the associated driving components to limit RF losses and signal degradation. For example, a radiating element positioned in the center of the front side 108-1 of the PCB 106-1 may be driven by an RF chain component 120-1 positioned in the center of the rear side 110-1 of the PCB 106-1. Although the RF chain components 120-1 are generally positioned directly across from the radiating element, in some embodiments, some RF chain components (e.g., filters and / or polarizers) may be located in other locations or on the front side 108-1 of the PCB.

[0063] Referring now to FIG. 8, shown therein is a detailed plan view of rear side 110-1 of PCB 106-1 in an isolated state.

[0064] Visible in FIG. 8 are multiple RF chain components 120-1 coupled to the rear surface 110-1 of the PCB 106-1 such that the spacing between the components can be visualized. Additionally visible in FIG. 8 is a depiction of an RF chain cluster 122-1. The RF chain cluster 122-1 includes a group of eight RF chain components 120-1 in a particular arrangement. The PCB 106-1 includes a total of twelve RF chain clusters 122-1. In variations, the number of RF chain clusters 122-1 and the number of RF chain components 120-1 within each RF chain cluster 122-1 can vary.

[0065] 9, there is shown a detailed perspective view of a single RF chain cluster 122-1 in isolation. The terms "top", "upper", "lower" and "bottom" are used throughout and are intended to describe the relative positions of the electrical components of the assembly 100-1. The terms are defined relative to the rear surface 110-1. Components in contact with the rear surface 110-1 are considered to be at the "bottom" of the three-dimensional stack. Components furthest from the rear surface 110-1 are considered to be at the "top" of the stack. "Up" and "down" are defined relative to the rear surface 110-1, with a vertical direction away from the rear surface 110-1 being defined as "upper", while a vertical direction towards the rear surface 110-1 is defined as "lower". A "vertical" direction is defined as perpendicular to the rear surface 110-1, while a "horizontal" direction is defined as parallel to the rear surface 110-1.

[0066] Visible in Figure 9 are several electrical components coupled to the rear surface 110-1 of PCB 106-1 (not shown in Figure 9), including RF chain component 120-1. In some examples, some components may be integrated into PCB 106-1, for example as striplines, or coupled to the front side 108-1 of PCB 106-1.

[0067] The electrical components include a filter 124-1, a system-in-package (SIP) 126-1, and a digital beam forming integrated circuit 130-1. Each SIP can include amplifiers, filters, and hybrid components. In the embodiment of FIG. 9, two filters 124-1 and one SIP form the RF chain component 120. When the RF chain component 120 is configured in a stacking configuration as shown in FIG. 9, it can be referred to as a stacked RF chain, stacked packages, or an RF chain component stack. In other embodiments, the number of each component in the stack can vary. In some embodiments, a hermetically enclosed monolithic microwave integrated circuit or other component can be used instead of a SIP. Each SIP can include multiple RF channels. The number of filters 124-1 in the stack can correspond to the number of RF channels in the SIP.

[0068] In embodiments using analog beamforming, an analog beamforming integrated circuit may be present and may include a high power amplifier. In some examples, the analog beamforming integrated circuit may be packaged in a SIP. In general, embodiments using analog beamforming will include a greater number of components / integrated circuits since the circuit design for analog beamforming may be more complex.

[0069] 9 shows a three-dimensional component stacking arrangement of the assembly 100. For example, the SIP 126-1 is stacked above the filter 124-1, which is arranged such that the two filters 124-1 are stacked on top of each other on the PCB 106-1. This three-dimensional component stacking arrangement results in a more space-efficient component arrangement. For a given volume and PCB 106-1 area, a greater number of electrical components can be placed on the PCB 106-1 when a three-dimensional component stacking arrangement is used than if a more traditional two-dimensional arrangement were used. For example, for a fixed component spacing, a two-dimensional component arrangement would require a PCB with a larger area to support the same number of components as a three-dimensional component arrangement. Additionally, a three-dimensional component arrangement is better able to withstand fatigue failure due to thermal variations.

[0070] In this embodiment, two filters 124-1 are stacked in series such that the bottom surface of the two filter 124-1 stack can be coupled to the rear surface 110-1 of the PCB 106-1 while the top surface of the two filter 124-1 stack is free to receive another component above. In other embodiments, more filters 124-1 may be assembled into a single stack.

[0071] The SIP 126-1 is coupled or attached to the upper surfaces of the two filters 124-1 such that the SIP 126-1 is above both filters 124-1 (the filter stack).

[0072] In this embodiment, the component stack feeding the two radiating elements may include two filter modules, the components being stacked vertically on top of each other.

[0073] The stacks can be stacked vertically, and the stacks can be placed horizontally on PCB 106-1.

[0074] In other embodiments, other component stacking arrangements can be used.

[0075] The volumetrically efficient component arrangement illustrated in Figure 9 can enable the construction of a DRA assembly having lower mass and volume. Because spacecraft launch costs and service life can be proportional to overall mass, a volumetrically efficient component arrangement can reduce the launch costs and service life of the spacecraft to which assembly 100 is coupled.

[0076] 10, shown therein is a detailed plan view of RF chain cluster 122-1. Through the use of SMD technology and a specific component layout, as depicted in FIG. 10, very dense component spacing is achievable along with very short RF and DC paths that result in lower losses and higher DC efficiency than other, more conventional layouts.

[0077] Referring now to FIG. 11, shown therein is a cross-sectional view of assembly 100-1.

[0078] 11, RF chain components 120-1 are in physical contact with interface plate 114. Assembly 100-1 is configured such that the drive electronics for assembly 100-1 are located on a single side (rear side 110-1) of PCB 106-1. This can provide easier and more effective thermal management of assembly 100-1.

[0079] The assembly 100-1 is additionally configured such that the higher heat producing RF chain components are located at the top of the three-dimensional arrangement of the RF chain 120-1 and closest to the interface plate 114-1. In such a configuration, heat can be easily conducted from the top RF chain components, including the SIP 126-1, into the interface plate 114-1. Heat flow 142-1 can be seen in FIG. 11 which depicts the direction of heat flow through the assembly 100-1.

[0080] In some embodiments of the assembly 100-1, the contact surfaces of the interface plate 114-1 and the RF chain component 120-1 can be treated to promote heat transfer from the RF chain component 120-1 to the interface plate 114-1. For example, the contact surfaces of the interface plate 114-1 and the RF chain component 120-1 can be polished to improve surface contact or can be treated with a thermal compound to promote heat transfer across the RF chain component 120-1-interface plate 114-1 interface.

[0081] Referring now to Figure 12, shown therein is a cross-sectional view of assembly 100-1 of Figures 1-3 and 11. Additionally depicted is heat pipe 138-1, as well as spacecraft 134-1 and heat flow 142-1.

[0082] Spacecraft 134-1 is the spacecraft on which assembly 100-1 is mounted and operated. Spacecraft 134-1 may include a satellite. In some embodiments, the satellite may be a Low Earth Orbit (LEO) satellite. In other embodiments, assembly 100-1 may be mounted on another vehicle or on a stationary or mobile structure, as previously described.

[0083] Heat pipe 138-1 comprises the thermal management components of spacecraft 134-1. Heat pipe 138-1 may be the primary thermal path for spacecraft 134-1, with heat-producing components of spacecraft 134-1 positioned such that heat can be transferred into the heat pipe (e.g., through conduction) and thus away from the heat-generating components.

[0084] The heat pipe 138-1 must be maintained at a temperature below the operating temperature of the heat-generating component to allow for thermal transfer from the heat-generating component to the heat pipe 138-1. In some examples, the spacecraft 134-1 may further include a thermal radiator coupled to the heat pipe 138-1 such that heat may be radiated from the heat pipe 138-1 into space or transferred from the heat pipe 138-1 to the thermal radiator (e.g., a panel radiator, etc.) and from the radiator into space to reduce or maintain the temperature of the heat pipe 138-1 such that an effective thermal gradient is maintained.

[0085] The use of the spacecraft central heat pipe 138-1 for thermal management of the assembly can reduce the cost, complexity, mass, and volume of the assembly 100-1 because a separately designed and implemented heat removal system may not be required for the assembly 100-1. Additionally, the use of the spacecraft central heat pipe 138-1 can help avoid the need for additional heat transfer devices in the assembly 100-1 beyond the interface plate 114-1, or can help avoid the need to reconfigure or add to the spacecraft thermal management subsystem / infrastructure, such as by routing the spacecraft heat pipe on top of the assembly 100-1. The heat pipe can be routed above the spacecraft's Earth-facing panels, between the assembly 100-1 and the spacecraft's Earth-facing panels, or below the assembly 100-1 and into the spacecraft's Earth-facing panels. In other embodiments, the heat pipe can be routed anywhere in the spacecraft. In other embodiments, heat transfer techniques other than heat pipes may be implemented as part of the spacecraft thermal control subsystem and used to thermally manage assembly 100-1. In other embodiments, heat pipes may alternatively be mounted to the underside / opposite side of interface plate 114-1.

[0086] The assembly 100-1 can be configured such that the central radiating element 112-1 of the assembly 100-1 transmits RF signals at a higher power level than the peripheral radiating elements 112-1. As previously described, the driving components of each radiating element 112-1 are located generally directly opposite the radiating element on the other side of the PCB 106-1. As a result, the components associated with the central radiating element 112-1 generally consume more power during operation and generate more heat that must be dissipated. The heat pipe 138-1 in FIG. 12 is located relative to the central-most radiating element 112-1 of the assembly 100-1 such that the components that generate the most heat are closer to the heat pipe 138-1, thereby increasing the heat removal performance of the assembly 100-1.

[0087] The above description with reference to Figures 11 and 12 can be applied to the assembly 100-2. The heat transfer methods depicted in Figures 11 and 12 are identical in operation to the heat transfer methods that can be applied in the Rx assembly 100-2, and only differ in the configuration of the RF chain 120-2 and the interface plate 114-2 relative to the RF chain 120-1 and the interface plate 114-1. This is because different components of each RF chain will generate and dissipate heat, and different shapes of interface plates may be required.

[0088] Referring now to FIG. 13, shown therein is a perspective view of a portion of PCB 106-1 in an isolated state, according to an embodiment.

[0089] A single RF chain cluster 122-1 (depicted as transparent) can be seen in FIG.

[0090] PCB 106-1 is depicted as semi-transparent in FIG. 13, allowing radiation-shielding copper layer 140-1 to be seen through PCB 106-1 (i.e., radiation-shielding copper layer 140-1 is configured as an inner layer of multi-layer PCB 106-1).

[0091] 14, shown therein is a plan view of a portion of PCB 106-1 of FIG.

[0092] PCB 106-1 is depicted as semi-transparent, allowing radiation shielding copper layer 140-1 to be seen through PCB 106-1.

[0093] 14, a radiation shielding copper layer 140-1 is placed below the digital beam forming integrated circuit 130-1 because this component contains radiation sensitive components in the exemplary embodiment of the assembly 100-1.

[0094] In other examples, the radiation shielding copper layer 140-1 can include other shapes, sizes, and locations. In some examples, the radiation shielding copper layer 140-1 can include a complex compound shape including several non-intersecting copper regions or copper islands. In some examples, each non-intersecting copper region can be located on the same PCB layer or on a separate PCB layer. In some examples, the radiation shielding copper layer 140-1 can be configured and positioned to shield components other than the digital beam forming integrated circuit 130-1. In some examples, the filter components can be embedded in the PCB 106-1 and positioned below the radiating element 112-1. In another example, the filter components can be mounted on the front side 108-1 of the PCB and positioned below the radiating element 112-1. Such a configuration of the filter components can contribute to radiation shielding.

[0095] As previously described, using copper PCB layers as a radiation shield can result in a reduction in volume and mass for assembly 100-1 because separate radiation shielding components of greater mass and volume may not be required to be mounted external to PCB 106-1 to drive the performance of 100-1.

[0096] While Figures 13 and 14 depict PCB 106-1 of DRA assembly 100-1 in a transmit configuration, a similar shielding layer may be present in PCB 106-2, albeit of a different size and positioning, so that radiation-sensitive components of RF chain 120-2 on PCB 106-2 are shielded from external electromagnetic radiation to which assembly 100-2 may be exposed.

[0097] Although the above description provides examples of one or more devices, methods, or systems, it will be recognized that other devices, methods, or systems are possible within the scope of the claims as interpreted by one of ordinary skill in the art. [Explanation of symbols]

[0098] 100-1 Direct Radiating Array ("DRA") Antenna Assembly 100-2 Direct Radiating Array ("DRA") Antenna Assembly 102-1 Front Printed Circuit Board (PCB) Housing 102-2 Front Printed Circuit Board (PCB) Housing 104-1 Calibration Antenna 104-2 Calibration Antenna 106-1 PCB 106-2 PCB 108-1 Front side 108-2 Front side 110-1 Rear side 110-2 Rear side 112-1 Radiating element 112-2 Radiating element 114-1 Interface plate 114-2 Interface plate 116-1 Connector cover 116-2 Connector cover 118-1 Power Converter (EPC) 118-2 Power Converter (EPC) 120-1 RF Chain 120-2 RF Chain 122-1 RF Chain Cluster 124-1 Filter 126-1 System in Package (SIP) 130-1 Digital Beam Forming Integrated Circuit 134-1 Spaceship 138-1 Heat pipe 140-1 Radiation shielding copper layer 142-1 Heat flow

Claims

1. a printed circuit board ("PCB") having a first side and a second side opposite the first side; a thermal interface plate disposed generally parallel to the printed circuit board ("PCB"); a plurality of radiating elements mounted on the first side of the printed circuit board ("PCB"); a plurality of radio frequency ("RF") chains mounted to the second side of the printed circuit board ("PCB") and to the thermal interface plate, each one of the plurality of radio frequency ("RF") chains being coupled to a respective one of the plurality of radiating elements, positioned proximate to a respective one of the plurality of radiating elements, and thermally coupled to the thermal interface plate; a plurality of beam forming circuits mounted on the second side of the printed circuit board ("PCB"), each of the radio frequency ("RF") chains being connected to at least one of the plurality of beam forming circuits; A direct radiating array ("DRA") antenna, including:

2. 2. The direct radiating array ("DRA") antenna of claim 1, wherein the radio frequency ("RF") chains are arranged in a plurality of stacks, each one of the plurality of stacks being mounted to the second side of the printed circuit board ("PCB") and extending generally perpendicular to the second side of the printed circuit board ("PCB").

3. The direct radiating array ("DRA") antenna of claim 1 or 2, wherein the radiating elements are patch radiating elements.

4. 2. The direct radiating array ("DRA") antenna of claim 1, wherein the printed circuit board ("PCB") includes one or more radiation-shielding copper layers embedded within the printed circuit board ("PCB") and positioned to shield electrical, electronic, or electromechanical components of the direct radiating array ("DRA") antenna from radiation.

5. The direct radiating array ("DRA") antenna of claim 1 , wherein the thermal interface plate includes a plurality of fluid channels.

6. 10. The direct radiating array ("DRA") antenna of claim 1, wherein the thermal interface plate, when mounted on a movable or stationary structure, acts as the sole thermal spreader and the direct radiating array ("DRA") antenna's conductive and radiation exchanging interface with the movable or stationary structure.

7. The direct radiating array ("DRA") antenna of claim 6, wherein the mobile or stationary structure is a spacecraft.

8. The direct radiating array ("DRA") antenna of claim 6, wherein the mobile or stationary structure is a low earth orbit satellite.

9. The direct radiating array ("DRA") antenna of claim 2 , wherein each of the plurality of stacks is connected to the thermal interface plate via one or more thermal interface materials.

10. a printed circuit board ("PCB") having a first side and a second side opposite the first side; a plurality of radiating elements mounted on the first side of the printed circuit board ("PCB"); a plurality of radio frequency ("RF") chains each coupled to a respective one of the plurality of radiating elements, the plurality of radio frequency ("RF") chains being arranged in a plurality of stacks, each respective one of the plurality of stacks being mounted to the second side of the printed circuit board ("PCB") and extending generally perpendicular to the second side of the printed circuit board ("PCB"); A direct radiating array ("DRA") antenna, including:

11. The direct radiating array ("DRA") antenna of claim 10, wherein the radiating element comprises a patch radiating element.

12. The direct radiating array ("DRA") antenna of claim 1 , wherein the beamforming circuitry is configured to perform digital beamforming.

13. The direct radiating array ("DRA") antenna of claim 1 , wherein the beamforming circuitry is configured to perform analog beamforming.

14. 11. The direct radiating array ("DRA") antenna of claim 10, further comprising a plurality of beam forming circuits mounted on said second side of said printed circuit board ("PCB"), said beam forming circuits configured to perform digital beam forming.

15. 11. The direct radiating array ("DRA") antenna of claim 10, further comprising a plurality of beam forming circuits mounted on said second side of said printed circuit board ("PCB"), said beam forming circuits configured to perform analog beam forming.

16. Systems, methods, and devices generally and specifically described herein.

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